First, we need to have a strong relationship with God; we must make sure that we are regularly spending time with God through His Word and in prayer. It is easy to get so busy working for God that we start to ignore our relationship with God. As a missionary it can also be easy to focus on the aspect of raising support. The Bible says that God will supply what I need, not based on all my efforts, but through Christ. Matthew 6:33 says that if we seek God's Kingdom first then all of the other things we need will be added to us.
Second, we need to stay focused on the call of God in our life. There will always be hard times as a minister and as a missionary there can be the added stress of living in a different nation than where you are born. While I can happily say that I enjoy living and ministering in Germany and Europe there are things here that are different from where I grew up. That is not to say that one is right and the other is wrong, it is just different. When we are frequently faced with things that are different than what we are used to it can be a problem, this is where culture shock comes in. For me the solution is to focus on what God has called me to do. If God has called me to be in a certain place then He will give me the grace to live, work, and succeed there.
Third, we need to develop strong personal relationships. Thankfully this is an easy one for me; I work with an awesome group of people here in Germany. It is important to have good personal relationships with people who can help to encourage us and support us in what God has called us to do. We were not designed to work and live alone so we must have some good friends to help us along the way. These three things have been a help to me as a missionary and I plan on continuing to use this missionary maintenance plan.